Abstract

Direction of arrival (DOA) estimates made simultaneously by a vector sensor and a co-located 1.4 m long horizontal line array (HLA) are compared. The 8-channels of data, corresponding to four HLA pressuresensors and a vector sensor (3-orthogonal particle accelerationsensors + 1 pressuresensor), were coherently recorded by an autonomous bottom-deployed system. The system was deployed 4 km off the coast of Panama City, FL, in water 20 m deep. Recordings were made of a series of 1–4 kHz transmissions (100-ms duration) produced by source suspended 12 m below a drifting vessel. GPSmeasurements of the source location for each transmission show a source heading changing by 90 degrees relative to the sensor system as the source passes to within 200 m before opening to range 1200 m. The performance of DOA estimates from vector sensormeasurements of active intensity and from HLA beamforming, using both conventional methods and compressive sensing, are assessed relative to the measured source bearing. At certain source locations DOA estimates deviate significantly from the source bearing. This effect is shown to be caused by destructively interfering modes, which can produce DOA estimates in the opposite direction of the source bearing.